AUTOMATED SHORELINE ELEVATION MEASUREMENT FROM HIGH-RESOLUTION TOPOGRAPHY: APPLICATIONS TO QUANTIFYING LANDSCAPE DEFORMATION

Shorelines and terraces have long been used as markers of landscape deformation, in applications from active tectonics to isostatic rebound. Traditionally, the elevation of these geomorphic features was measured from slope-parallel profiles obtained from field surveys or more recently, high-resolution topography. Manual profile selection and analysis limit the output resolution of elevation data, however. The growing availability of high-resolution topography presents the opportunity to automate elevation calculation and utilize the entirety of a geomorphic surface instead of 2D profiles.

We have developed a new ArcGIS toolbox called PaleoElev to automate calculation of shoreline elevation. Elevation calculations are based on previously published methods, where the second derivative of the shoreline profile is used to define the wave cut platform and sea cliff surfaces. The intersection of these projected surfaces is the elevation of the shoreline. PaleoElev creates swath profiles from high-resolution topography to perform these projections, which takes into account the total continuous shoreline surface. This tool requires minimal manual input by the user and produces output elevation points at a user-defined spacing.

The application of the tool to Lake Bonneville shorelines along the Wasatch Front in northern Utah produced higher-density results than previous studies utilizing manual profile analysis. Results from this analysis indicate that shoreline geomorphology may be more complex than previously recognized and more clearly depict tectonic deformation of the surface by the Wasatch Fault Zone since the late Pleistocene.

While originally developed for application to shorelines, the PaleoElev tool has a broad range of potential future applications, including geomorphic and neotectonic applications. Future development of the tool will include diversifying the tool to function with a broader range of geomorphic features.